Infections involving the human gastrointestinal tract and other body lumens are extremely common, involving many millions of people on an annual basis. These infections are responsible for significant illness, morbidity and death. One of the most common gastrointestinal infections is a chronic infection with Helicobacter pylori (H. pylori), a bacterial pathogen that infects the stomach and duodenum. In industrialized nations such as the United States, H. pylori may be found in 20% or more of the adult population. In some South American countries, the H. pylori infection rate approaches 90%. Although infection with H. pylori can be asymptomatic, in a significant minority of infected people it is associated with serious conditions including gastritis, gastric ulcer, duodenal ulcer, gastric cancer, and gastric lymphoma. H. pylori is believed to be responsible for approximately 90% of all reported duodenal ulcers, 50% of gastric ulcers, 85% of gastric cancer, and virtually 100% of gastric lymphoma.
The most common treatment currently available for H. pylori infection is a complex antibiotic regimen involving three or four expensive drugs given over a two-week period. Even with antibiotic treatment, 20% or more of those treated are not cured of their infection. Further, the powerful antibiotics used are not well tolerated by some patients, variously causing allergic reactions, nausea, an altered sense of taste and diarrhea. In addition, antibiotic resistance by this and many other pathogenic organisms is growing rapidly. Up to 50% of H. pylori isolates are now resistant to one or more of the best antibiotics known to cure the infection. No vaccine is yet available for H. pylori, despite years of intensive effort.
Therapeutic methods that do not rely solely on drugs to treat disease thus have significant potential advantages over antibiotic therapy for bacterial infections. Photodynamic therapy (PDT) is a light therapy that includes pretreatment with a photosensitizing drug, followed by illumination of the treatment area to kill cells having a high concentration of the drug, which preferentially absorbs light at specific wavelengths. A typical application of this method is to debilitate or destroy malignant tumor cells that have preferentially retained the photosensitizing drug, while preserving adjacent normal tissue. Direct deactivation or killing of H. Pylori and other microorganisms has been demonstrated using light, without requiring pretreatment with a photosensitizer.
Broad deployment of light therapy for H. Pylori and other intraluminal infections will require practical and reliable light sources with which to effect such treatment. Access can be gained to some treatment sites within the body, including interior surfaces of the digestive tract, using light sources configured as elongate probes that can be guided through an external orifice into the body and to the treatment site. One such minimally invasive approach is to deliver light to the interior of a body lumen through an optical fiber that is optically coupled to a remotely located high power laser. This approach to light therapy is expensive, generally lacks portability, and is impractical for delivering light to large intraluminal treatment areas.
An alternative approach for developing minimally invasive probes for intraluminal light therapy is to utilize electrically excited light-emitting devices such as light-emitting diodes within a probe. One problem associated with this approach is that the light-emitting devices confined within an elongated probe produce waste heat when electrically excited, thereby significantly limiting the maximum average light output power achievable from the probe without thermally damaging the light-emitting devices, and without exceeding safe temperatures for exposure of the probe to body tissue at the treatment site.
Additionally, it would be advantageous for a probe to be made physically flexible to be safely guided through narrow passages in the body and positioned at a treatment site. Attempts to address these problems may be found in U.S. Pat. Nos. 5,800,478 and 5,576,427. However, each one of these references suffers from a variety of disadvantages, including one or more of the following disadvantages: the probe is lacking flexibility in the plane of a substrate on which the array of light-emitting devices is constructed, and thermal dissipation of the probe at high light output power is not addressed.
Thus, a great need exists for new devices and systems to deliver light to an interior of a lumen, for treatment of H. pylori and other intraluminal infections. There also exists a need for apparatus and methods to deliver light to lumens of the body in a safe and effective manner. In addition, generally there exists a need for the effective delivery of light to an interior space that may benefit from treatment with radiation including light.